Buying a sex toy can be daunting. There’s always uncertainty when you buy from a new company—it can be tough to tell whether the materials are high quality, whether they’re safe to be in contact with your most sensitive areas, and what sorts of wear and tear you can expect. But I have a shortcut to help you make the most informed sex toy purchases: the iPhone Rule.

The iPhone isn’t designed to be in direct, prolonged contact with anyone’s genitals, and I advise against trying to use one as a sex toy. But if you did, it would probably be fine, and that’s because of what it’s made out of—glass, metal, and if you have a case, silicone. Yes, many other materials go into making a phone, and not every case is silicone, but I’ve found that this is a good way to remember what to look for in a sex toy. Naturally, all of these materials have differing grades of quality, but glass, metal, and silicone are the big three you want to be looking for when shopping for a sex toy.

Special offer for Gear readers: Get WIRED for just $5 ($25 off). This includes unlimited access to WIRED.com, full Gear coverage, and subscriber-only newsletters. Subscriptions help fund the work we do every day.

If you buy something using links in our stories, we may earn a commission. This helps support our journalism. Learn more.

Good Old Glass

This might not be the first material that jumps to mind when you think of sex toys, but it’s a tried and true option for solid-state, non-vibrating sex toys like glass dildos and glass butt plugs. When you’re shopping for a glass sex toy, make sure the packaging or website states explicitly that it’s made out of borosilicate glass. Glass sex toys are safe to use with every kind of lube, and only need to be hand-washed with soap and water to get clean.

This is the same kind of durable glass used to make scientific equipment and it’s fully nonporous. Being nonporous is important for sex toys because if there are no pores, there’s nowhere for bacteria to hide out when you wash them. If a sex toy is porous, it’s likely only single use, because you’ll never really be able to get it clean and it will discolor and degrade over time. If it’s unclear what kind of glass a sex toy is made out of, don’t buy it. This goes triple for glass toys because if they’re made improperly they can be potentially dangerous! If the company’s packaging or website is indirect or unclear, it’s usually time to move on. There are some exceptions though, so if a particular toy catches your eye it never hurts to email the company directly—most have “contact us” sections for just such occasions.

The toy we recommend above didn’t have the exact information we were looking for listed on its website, but Kindred Black cofounder Alice Wells confirmed to us that each of its glass sex toys is hand-blown from borosilicate glass right in the US.

Cold Hard Metal

Metal sex toys are a little less common than ones made from silicone or plastic, but like glass, they’re incredibly durable and safe to use with every kind of lube. Unlike glass, some metal toys can provide safe internal vibration options. What you want to look for in a metal sex toy is similar to what you look for in a glass toy—clarity about what it’s made out of and how.

Metal sex toys should be made from surgical steel, also referred to as 316 or 316L stainless steel.  This kind of steel is a nonporous material that has been tested for biocompatibility and is often used in medical applications like surgical pins, or even piercings. The parts of the body that it’s going to be in contact with are important for determining whether a material is safe. It’s worth noting that surgical steel can potentially corrode over time when implanted in certain parts of the body; 316 stainless steel can see some significant corrosion in solutions with a pH of 1.58 or lower. Thankfully vaginal pH typically fluctuates between 3.8 and 5, rectal pH between 7 and 8, and salivary pH between 6.3 and 7.3. All that means is there’s a near-zero chance of a surgical stainless steel sex toy being corroded by coming into contact with any of the usual places a sex toy might end up—even if you use it every day.

It’s a tried and true material and it’s built to last. Just like glass, you’ll want to scrub it with soap and water to clean it.

Slippery Silicone

Silicone is the most widely used sex toy material, and also the hardest to identify. Just about every sex toy maker has different words they use to describe the silicone they use. I’ve seen body-safe, medical grade, body-friendly, hypoallergenic, and tons of other terms thrown around, and I’ve vetted each one.

There are a couple with a solid body of research behind them, along with some common testing standards: platinum-cured silicone and food-grade silicone. Food grade is a label regulated by the FDA, and it means the silicone has been tested to make sure it doesn’t leach harmful chemicals into food. Platinum-cured silicone is safer than standard (peroxide-cured) silicone because the chemicals used to make the silicone are more completely consumed during the process, leaving nothing behind to leach into your body. Platinum-cured silicones are surprisingly odorless for this reason.

Medical grade is a label you’ll see pretty often, but if it’s not backed up with the specific regulatory body or testing standard used to determine that it’s medical grade, it leaves me wondering why that hasn’t been disclosed.

What If There’s No Information?

You can usually contact the company you’re interested in and ask them what the sex toy is made of. If they don’t respond, or if there’s no way to glean this information, you probably should avoid the product. No matter how cool the toy is, if you don’t know what it’s made out of, that’s because someone in the supply chain has decided not to tell you, and that is a red flag. Sex toys should be treated like medical devices and, as a potential buyer, you deserve specific, clear, and robust information about what you’re putting in your body.

You May Also Like

Astronomers discover immense swarms of sunspots that could lead to solar flares

A pair of massive sunspot swarms, some large enough to devour the…

Scientists discover for the first time that sperm defy one of Newton’s laws of PHYSICS

Scientists have discovered that the way sperms swim defies Newton’s law of…

Ancient trees help to keep forests alive by passing down golden genes

They may make up just one per cent of the world’s tree…

Fake Walmart News Release Spurs Spike in Little-Used Cryptocurrency Litecoin

The price of litecoin, a little-used cryptocurrency, spiked in early trading Monday…